This invention is particularly concerned with a nuclear reactor installation using a pressurized-water reactor, its pressure vessel being surrounded by a concrete wall formed by a reinforced-concrete structure, provided for containment of the vessel in the event its side wall ruptures, as well as for biological reasons.
The Dorner et al U.S. Pat. application Ser. No. 315,932, filed Dec. 18, 1972, on which U.S. Pat. 3,898,126 issued Aug. 5, 1975, discloses a nuclear reactor installation of the above general type but with the pressure vessel's side wall surrounded by a layer of insulating concrete with a layer of steel balls or spheres of ceramic material or other spherical filler bodies positioned between this layer of insulating concrete and the pressure vessel's side wall. The layer of insulating concrete engages the concrete wall provided by a reinforced-concrete structure, and the radial force from the vessel's side wall is transmitted to this concrete wall via the two layers, a sheet metal lining being interposed between the two layers. The reinforced-concrete structure has its wall contacted by the thermally insulating concrete layer, provided with a cooling system.
The purpose of the above construction is to provide a containment of the pressure vessel's side wall in the event it ruptures, the cooling system of the concrete structure relieving the latter from excessive thermal stressing and, the reactor being promptly scrammed in the event of such an accident, to allow time for removing the residual and decay heat from the core via the usual emergency core cooling system. However, the invention of the above application specifically concerns restraint of the intercept ring on the cover of the pressure vessel, which is done via a special design of hooks, the concrete structure being vertically reinforced to carry the tension of the hooks should they be needed to hold down the intercept ring.
Again in the case of a pressurized-water reactor installation, the Michel U.S. application Ser. No. 464,238, filed Apr. 25, 1974, describes a construction wherein the pressure vessel is encased by plural layers of separable concrete segments held against radial force from the pressure vessel's wall by high tensile steel cylinders, relieving the concrete wall formed by the concrete structure, from being stressed by such force. The proportions of the parts are such that when the vessel is in operation its radial expansion is resisted by the steel cylinders so that the encasement is placed under compression, and when the reactor is cold, this compression is relieved so that the encasement's segments may be removed for inspection of the pressure vessel's side wall.